This invention relates to a print head for a dot printer. Various types of print head are used for a dot printer. The prior art print head is generally constructed and operated in the following manner. Electromagnets are separately manufactured in the same number as the print wires used. The electromagnets are fitted to a suitable frame. When the electromagnets are energized, the corresponding wires are pushed to a platen, thereby impressing dots on a sheet of print paper by means of the forward end printing portion of a print wire. However, the customary practice to separately produce many electromagnets has the drawbacks that a large number of parts are required; and the working, assembly and adjustment of parts consume much time, thus increasing the cost of a print head. To eliminate these difficulties, various print heads have been proposed, but without success.
One of the prior art proposed print heads in constructed, as shown in FIGS. 1 and 2, by producing a magnetic circuit in one piece to facilitate the integral manufacture of a plurality of electromagnets constituting an electromagnet unit. Referring to a magnetic circuit member denoted by the general reference numeral 18, the parts indicated by the reference numerals 10, 12 are respectively a pole piece and yoke jointly constituting a magnetic circuit of one electromagnet. The pole piece 10 is fitted with a magnetizing coil (not shown). When current runs through the coil, then the pole piece attracts an armature (not shown) lying near the pole piece and yoke. This attraction causes dots to be impressed by a print wire (not shown). The magnetic circuit member 18 of FIG. 1 can be easily assembled into nine electromagnets. This construction can indeed prominantly eliminate the aforesaid drawbacks of the prior art print head. However, this type of the known print head has been found still to have defects requiring improvement. The reason for this is as follows. As seen from FIG. 1, the yokes 12 extend in spaced relation for a considerable distance. Since the magnetic circuit member 18 is manufactured mainly by lost wax casting, the yokes 12 are invariably bent outward as illustrated in FIG. 2. The sections defined by dots-dash lines denote the proper position 12a of the yoke 12. The magnetic circuit member 18, of which the yokes 12 are bent outward cannot be put to practional use just as manufactured, making it necessary to carry out the subsequent correction of the defective portion. This correction which is generally undertaken by the hand calls for high skill and consumes a great deal of time. Accordingly, it has been demanded to develop magnetic circuit elements free from the above-mentioned deformation.